The laying of drains in the ground is generally performed by machines having a movable structure of the bulldozer type and a tooth which penetrates into the ground and which is drawn by the said structure.
The most advanced of these machines have a device for coupling the tooth to the structure, which is deformable and permits the tooth to maintain a substantially constant direction and average depth, whilst the movable structure follows local unevennesses, bumps or depressions in the ground.
The known coupling device comprises a tooth support which slides in a slide with which the structure is equipped. The considerable stresses to which the slide is subjected lead to frequent breaking and a lack of stability.